Acute Aortic Disease.. - Index of

Endovascular Thoracic Aortic Stent Grafting 305
DISCUSSION AND COMMENTARY
Editor’s Counterpoint
(Based on Elefteriades J. “Endograft Therapy for Thoracic Aortic Aneurysms:
Wave of the Future or The Emperor’s New Clothes,” an invited editorial in press
in the Journal of Thoracic and Cardiovascular Surgery, by permission.)
As a profession, cardiothoracic surgeons owe a debt of gratitude to
Dr. Bavaria and colleagues for spearheading these exciting clinical investigations
into novel endovascular therapies for aneurysm disease.
It is important for medical science to evaluate endografting of aneurysms
with enthusiasm for this new modality, but, at the same time, a grain of skepticism,
or at least realism. Multiple reasons to be cautious can be cited.
Conceptual issues. First, some authorities question the very concept of
repair of an expanding cylindrical structure by means of a graft placed within its
lumen. Stents, it is pointed out, were developed to keep arteries from closing in
(as in coronary angioplasty), not to keep them from expanding outward. How can
a graft placed inside an enlarging aorta—and not attached to the aorta—prevent
the inexorable expansion of that aorta? Some say the graft would have to go outside,
not inside, the aorta—a concept that was tried and failed many years ago.
To control a herd of cattle, the analogy goes, the wooden pen has to go outside
the cows; an internal endograft is like putting the pen inside the herd. The concern
is that the inexorable expansion of the aorta will ultimately leave the endograft
behind, “ignoring” it, so to speak. Another conceptual issue concerns
continued pressurization of the aneurysm sac by intercostal or lumbar vessels.
Yet another conceptual issue concerns the surgeon’s understanding that the
strength of the aorta resides in the adventitia, which is not incorporated in any
way by the endograft.
Short duration of follow-up of an indolent disease. This line of reasoning
leads to the second major concern: Thoracic aortic aneurysm, though ultimately
lethal, is an indolent disease. Many years are generally required from the time of
diagnosis to the time of aneurysm-related death, especially with small to moderate
size aneurysms (Fig. A) (2). To have patients alive at one or two years is not at all
reassuring. These patients would probably still be alive absent any directed therapy
whatsoever. As longer term follow-up becomes available through the
EUROSTAR investigation of endografting for abdominal aortic aneurysm, this
concern literally comes to life, with mortality and rupture rearing their ugly heads
as the aneurysm disease expresses its natural history, even after “successful”
endografting. The EUROSTAR study of endografting for abdominal aortic aneurysms
is much more “mature” than corresponding studies of thoracic aortic
aneurysm. In Figure B, it can be noted that endoleak becomes increasingly
common as duration of follow-up is extended (3). It appears that nearly half of
patients will suffer diagnosed endoleak as follow-up becomes extended toward
the five-year point. In this context, we need to keep in mind that the word
“endoleak” is itself a euphemism for failure of treatment. It has been demonstrated